The present invention relates to a device for the inspection of ventilation or air-conditioning ducts belonging to ventilation and air-conditioning systems with which, in particular, buildings are equipped, this device also being used for the inspection of other types of conduits, such as those of sewerage networks.
Most existing buildings constructed during the last thirty years are equipped with ventilation or air-conditioning systems which make it possible, on the one hand, to discharge outwards the pollution and contaminated air contained inside the buildings and, on the other hand, to replace this contaminated air by outside air, called new hygienic air. The discharge of the contaminated air and its replacement by new hygienic air are ensured by means of conduits or ducts which form more or less complex networks.
Access to such ventilation or air-conditioning systems, in particular their ducts, especially for inspecting and maintaining them, is difficult because they are located in the false ceilings or the partitions or else are incorporated into the carcass of the buildings. The same access problem arises where other types of conduits, such as buried pipelines, are concerned.
Moreover, the shape of the air ducts or conduits encountered in such systems is highly variable (round, oval, rectangular, square or triangular duct cross sections), and the dimensions of these ducts or conduits are also highly variable and may range, for example, from 80 mm to 1200 mm in diameter for ducts of circular cross section and from 100xc3x9750 mm to several square metres for ducts of rectangular cross section, no standard covering the dimensioning of ducts of rectangular cross section. Various materials are used for manufacturing these ducts (sheet metal, concrete, glass fibre, wood, textiles), and the method of assembling the various portions of ducts forming a network is also highly variable (assembly by flanges, by frames, by interlocking, etc.), with or without the interposition of joints which, as soon as the systems are commissioned, give rise to more or less serious leaks.
Furthermore, as the years go by, dust and other particles are deposited on the inner walls of the ducts and give rise to undesirable phenomena involving an increase in the aeraulic pressure drops, whilst at the same time producing conditions which are extremely favourable to the proliferation of microorganisms, and increasing the risks of fire.
There are, admittedly, cleaning methods and apparatuses for ducts or conduits of ventilation and air-conditioning systems. For example, the document WO-93/24246 relates to a device for the pneumatic cleaning of conduits, which is introduced and displaced inside a conduit to be cleaned and which generates a plurality of air jets there by means of nozzles. Under the same heading, mention may also be made of French Patent No. 2,715,086. However, since these cleaning devices act at locations inaccessible to the human eye, such as ducts housed in a false ceiling or incorporated into partitions, or bricked-in vertical hoppers, it is impossible for the operators to check the displacement and effectiveness of such devices visually during use or to verify afterwards the work which has been carried out by these cleaning devices.
Devices for cleaning ventilation ducts by means of air jets or liquid jets are also known, which already comprise a video camera making it possible to inspect the interior of the duct simultaneouslyxe2x80x94see European Patent Application No. 0560611, U.S. Pat. No. 5,311,641 or German Utility Model No. 8513770. In all these documents, the means for the ejection of air jets or liquid jets, and also the camera, are carried by a carriage which rolls on the bottom of the duct. This solution has many disadvantages:
complexity in the production of the movable assembly which comprises wheels and their drive means;
difficulty or impossibility for the carriage to pass through ducts having small dimensions or ducts in which obstacles are encountered (flow-metering flaps, fire barrier flaps, sound traps);
impossibility for the carriage to pass through some elbows, through branch connections offset in terms of height (with respect to the bottom of the main duct), through vertical ducts or through ducts inclined at a high gradient;
unsuitability of the device, particularly because of its weight, with regard to flexible ducts or ducts made of fragile material, in particular of glass fibres (the fibres being torn off by the wheels of the carriage).
The object of the present invention is to avoid all these disadvantages by providing a device designed for the visual inspection of the ducts or conduits of ventilation and air-conditioning systems, particularly with regard to the cleaning of these ducts, the device proposed by the invention being capable of being used, whatever the dimensions of the ducts to be inspected, the component materials of these ducts, the geometric complexity of the network of ducts of the ventilation or air-conditioning system in question and the direction (horizontal, vertical or oblique) of the conduits to be inspected.
To achieve this, the subject of the invention is a device for the inspection of ventilation or air-conditioning ducts and of other conduits, which comprises essentially a movable head intended to be introduced into a duct or a network of ducts to be inspected or other conduit or network of conduits, the movable head containing a video camera connected to external means for the display and/or recording of the images of the interior of the duct or conduit, and this movable head comprising means for the ejection of air jets, directed towards the walls of the duct or conduit in order to ensure the support and advance of the said movable head, these ejection means being connected to an external compressed-air source.
Such a device thus makes it possible to pick up images of the interior of the ducts, at the same time transmitting them to an operator located at a distance. Preferably, the movable head carries lighting means useful for an optimum pick-up of the images inside the duct, these lighting means advantageously consisting of a series of small lamps or of light-emitting diodes arranged in a circle around the lens of the camera. Preferably, the lighting means have a variable light intensity which is adjustable, in particular, as a function of the cross section of the duct to be inspected and also of the nature of the inner surface or of the component material of this duct or else of its inner covering.
According to a preferred embodiment of the device which is the subject of the invention, the abovementioned ejection means are arranged so as to direct the air jets in an oblique direction opposite to the lens of the camera, in order to advance the movable head inside the duct or conduit to be inspected. A xe2x80x9cdynamicxe2x80x9d device is thus obtained, which ensures not only the support of the movable head, but also the advance of the latter in the duct, for the purpose of inspecting this duct over a particular length, at the same time eliminating any structure of the carriage type and its disadvantages.
In a practical embodiment, the movable head is composed of a first part of cylindrical and hollow general shape, serving as a housing for the camera and carrying the possible lighting means, and of a second part of frustoconical general shape, attached to the first part and comprising a central compressed-air intake extended by oblique inner channels opening out via compressed-air outlet orifices distributed on the periphery of the said second part. This movable head is connected, by means of a flexible compressed-air pipe joined to its central compressed-air intake, to an external apparatus comprising at least a compressor and a control module with a power source for the camera and/or lighting and with a video monitor.
What is thus obtained as a whole is a device which has small dimensions and a small weight and which is displaced inside the duct or conduit to be inspected by means of the effect of the compressed air projected at high speed and which, during its advance, permanently supplies images of the interior of the duct which are capable of being displayed on the checking video monitor and which, of course, may also be recorded by a video recorder, thus making it possible to ascertain the internal state of the duct. It will also be noted that the air jets ensure by themselves that dust is removed from the inspected duct, the orientation of these jets being such that the dust raised does not obstruct the camera""s xe2x80x9cvisionxe2x80x9d.